FUKUOKA -- Passing your twilight years in Japan used to entail long days of contemplation and an austere diet of tofu. Sound dull? The good news is that doctors these days recommend an active social life for a happy, healthy old age. The bad news is, according to medical practitioner Magoe Ando, you'll still need to adopt a strict diet -- and well before your hair turns gray.

For 40 years, Ando has advocated a diet of unrefined, low-calorie foods and, at 83, he's a sprightly example of its apparent benefits. Born in Niigata Prefecture in 1918, he was an only child and spoiled with fat- and sugar-rich foods. He believes this exacerbated his already sickly disposition. After moving to Fukuoka aged 15, in his early 20s he began experimenting with his diet to improve his health.

What initially steered his experiments was a study he read on the Hunza people from the mountain valleys of northern Pakistan and Afghanistan, whose lean, nutritionally balanced diet is believed to be why they are among the world's longest-living peoples. After adopting eating habits similar to the Hunza's, Ando's condition improved vastly. The diet he began then and still advocates now as a doctor merges with macrobiotic principles. Derived from the Greek "macros" (large) and "bios" (life), the word "macrobiotic" was first coined by Hippocrates and has been used throughout history. Since the late 1920s, however, it has come to mean a diet of fresh, nonprocessed whole foods, as defined by Japanese writer-philosopher George Ohsawa, the founder of modern macrobiotics. Ohsawa advocated such a diet in the belief that it cleanses the body of toxins that can lead to chronic illness. However, in its strictest form, a macrobiotic diet can be so limiting as to cause nutritional deficiency. Today, Ohsawa's principles are usually used only as a guideline.